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Banū Mūsā
various inventions | major_works = Book of Ingenious Devices, Book on the Measurement of Plane and Spherical Figures | influences = Apollonius of Perga, Ptolomy, Galen, Al-Maʾmūn, Mūsā ibn Shākir, Yahya ibn Abi Mansur | influenced = Thabit ibn Qurra, Hunayn Ibn Ishaq, Ibn al‐Haytham, Naṣīr al‐Dīn al‐Ṭūsī, Gerard of Cremona, Leonardo Fibonacci, Jordanus de Nemore, Roger Bacon, Al-Jazari, Leonardo da Vinci }} 's treatise on mechanical devices. The manuscript was written in Arabic.]] The Banū Mūsā brothers ( , "Sons of Mūsā") were three 9th century PersianWhen Baghdad Ruled the Muslim World: The Rise and Fall of Islam's Greatest Dynasty, Hugh Kennedy, p. 254Professor Jeff Oaks, The University of Indianapolis http://facstaff.uindy.edu/~oaks/MHMC.htm scholars, of Baghdad, active in the House of Wisdom: *'Abu Ja'far Muhammad ibn Mūsā ibn Shākir' (before 803 – 873) ( ) ,al-Nadim, Fihrist, trans. Bayard Dodge, p. 646 who specialised in astronomy, engineering, geometry and physics. *'Ahmad ibn Mūsā ibn Shākir' (803 – 873) ( ) , who specialised in engineering and mechanics. *'Al-Hasan ibn Mūsā ibn Shākir' (810 – 873) ( ) , who specialised in engineering and geometry. The Banu Musa were the sons of Mūsā ibn Shākir, who had been a highwayman and later an astrologer to the Caliph al-Ma'mūn. At his death, he left his young sons in the custody of the Caliph, who entrusted them to Ishaq bin Ibrahim al-Mus'abi, a former governor of Baghdad. The education of the three brothers was carried out by Yahya bin Abu Mansur who worked at the famous House of Wisdom library and translation centre in Baghdad. Overview The Banū Mūsā brothers ("Sons of Moses"), namely Abū Jaʿfar, Muḥammad ibn Mūsā ibn Shākir (before 803 – February 873), Abū al‐Qāsim, Aḥmad ibn Mūsā ibn Shākir (d. 9th century) and Al-Ḥasan ibn Mūsā ibn Shākir (d. 9th century), were three 9th-century Iranian scholars who lived and worked in Baghdad. They are known for their Book of Ingenious Devices on automata (automatic machines) and mechanical devices. Another important work of theirs is the Book on the Measurement of Plane and Spherical Figures, a foundational work on geometry that was frequently quoted by both Islamic and European mathematicians. The Banu Musa worked in astronomical observatories established in Baghdad by the Abbasid Caliph al-Ma'mun as well as doing research in the House of Wisdom. They also participated in a 9th-century expedition to make geodesic measurements to determine the length of a degree. Life The Banu Musa were the three sons of Mūsā ibn Shākir, who earlier in life had been a highwayman and astronomer in Khorasan of unknown pedigree. After befriending al-Ma'mun, who was then a governor of Khorasan and staying in Marw, Musa was employed as an astrologer and astronomer. After his death, his young sons were looked after by the court of al-Maʾmūn. Al-Maʾmūn recognized the abilities of the three brothers and enrolled them in the famous House of Wisdom, a library and a translation center in Baghdad. Studying in the House of Wisdom under Yahya ibn Abi Mansur, they participated in the efforts to translate ancient Greek works into Arabic by sending for Greek texts from the Byzantines, paying large sums for their translation, and learning Greek themselves. On such trips, Muhammad met and recruited the famous mathematician and translator Thābit ibn Qurra. At some point Hunayn ibn Ishaq was also part of their team. The brothers sponsored many scientists and translators, who were paid about 500 dīnārs a month. If it wasn't for efforts of the brothers, many of the Greek texts that they translated would have been lost and forgotten. After the death of al-Ma'mun, the Banu Musa continued to work under the Caliphs al-Mu'tasim, al-Wathiq, and al-Mutawakkil. However, during the reign of al-Wathiq and al-Mutawakkil internal rivalries arose between the scholars in the House of Wisdom. At some point the Banu Musa became enemies to al-Kindi and contributed to his persecution by al-Mutawakkil. They were later employed by al-Mutawakkil to construct a canal for the new city of al-Jafariyya. Mathematics and Mechanics The Banu Musa looked at area and circumference quite a bit differently than the Greeks did. In the research they translated, the Greeks looked at volume and area more in terms of ratios, rather than giving them an actual number value. Most of them based such measurements relatively on another objects size. In one of their surviving publications the Kitab marifat masakhat al-ashkal (The Book of the Measurement of Plane and Spherical Figures) Banu Musa gave volume and area number values. This is evidence that were not just translating Greek material and recreating. They were actually building on concepts and coming up with some of their own original works. The most popular of their publications was the Kitāb al-Ḥiyal, which was mostly the work of Aḥmad, the middle brother, was a book filled with one hundred mechanical devices. There were some real practical inventions in the book including a lamp that would mechanically dim, alternating fountains, and a clamshell grab. Eighty of these devices were described as "trick vessels" that showed a real mastery of mechanics, with a real focus on the use of light pressure. Some of the devices seem to be replications of earlier Greek works, but the rest were much more advanced than what the Greeks had done.7 Automata Most notable among their achievements is their work in the field of automation, which they utilized in toys and other entertaining creations. They have shown important advances over those of their Greek predecessors. * The Book of Ingenious Devices describes 100 inventions; the ones which have been reconstructed work as designed. While designed primarily for amusement purposes, they employ innovative engineering technologies such as one-way and two-way valves able to open and close by themselves, mechanical memories, devices to respond to feedback, and delays. Most of these devices were operated by water pressure. * Qarasṭūn, a treatise on weight balance. * On Mechanical Devices, a work on pneumatic devices, written by Ahmad. * A Book on the Description of the Instrument Which Sounds by Itself, about musical theory. ''Book of Ingenious Devices'' The Banu Musa brothers invented a number of automata (automatic machines) and mechanical devices, and they described a hundred such devices in their Book of Ingenious Devices. Some of these inventions include: * Valve and plug valveOtto Mayr (1970), The Origins of Feedback Control, MIT PressDonald Routledge Hill, "Mechanical Engineering in the Medieval Near East", Scientific American, May 1991, pp. 64-9 (cf. Donald Routledge Hill, Mechanical Engineering) * Float valve * Feedback controller * Automatic flute playerTeun Koetsier (2001), "On the prehistory of programmable machines: musical automata, looms, calculators", Mechanism and Machine theory 36: 590-1 * Programmable machine * Mechanical trick devices * Hurricane lamp * Self-trimming lamp (Ahmad ibn Mūsā ibn Shākir) * Self-feeding lamp * Gas mask * Grab * Clamshell grab * Fail-safe system * Differential pressure The Banu Musa also invented "the earliest known mechanical musical instrument", in this case a hydropowered organ which played interchangeable cylinders automatically. According to Charles B. Fowler, this "cylinder with raised pins on the surface remained the basic device to produce and reproduce music mechanically until the second half of the nineteenth century." The Banu Musa also invented an automatic flute player which appears to have been the first programmable machine.Teun Koetsier (2001). "On the prehistory of programmable machines: musical automata, looms, calculators", Mechanism and Machine theory 36, p. 590-591. ''On mechanics'' Ahmad (c. 805) specialised in mechanics and wrote a work on pneumatic devices called On mechanics. Mathematics * Book on the Measurement of Plane and Spherical Figures, later edited by Naṣīr al‐Dīn al‐Ṭūsī in the 13th century. A Latin translation by Gerard of Cremona appeared the 12th century under the titles Liber trium fratrum de geometria and Verba filiorum Moysi filii Sekir. This treatise on geometry was used extensively in the Middle Ages, quoted by authors such as Thābit ibn Qurra, Ibn al‐Haytham, Leonardo Fibonacci (in his Practica geometriae), Jordanus de Nemore, and Roger Bacon. Some theorems included in this book are not found in any work of the Greek mathematicians. * Conic Sections of Apollonius of Perga, a recension of the Greek work, which was first translated to Arabic by Hilāl al-ḥimṣī and Thābit ibn Qurra. * Book on an Oblong Round Figure, which contains a description of procedure used to draw an ellipse using a string, now called the gardener's construction. * Reasoning on the Trisection of an Angle, by Aḥmad. * A treatise containing a discussion between Ahmad and Sanad ibn ʿAli. * Book on a Geometric Proposition Proved by Galen. ''Premises of the book of conics'' The eldest brother, Ja'far Muḥammad, wrote a critical revision on Apollonius' Conics, called the Premises of the book of conics. ''The Book of the Measurement of Plane and Spherical Figures'' The Banu Musa's most famous mathematical treatise is The Book of the Measurement of Plane and Spherical Figures, which considered similar problems as Archimedes did in his On the Measurement of the Circle and On the Sphere and the Cylinder. ''The elongated circular figure'' The youngest brother, al-Hasan (c. 810), specialised in geometry and wrote a work on the ellipse called The elongated circular figure. Astronomy They made many observations and contributions to the field of astronomy, writing nearly a dozen publications over their astronomical research. They made many observations on the sun and the moon. Al-Ma’mun had them go to a desert in Mesopotamia to measure the length of a degree. They also measured the length of a year to be 365 days and 6 hours. ''Book on the motion of the orbs'' In physics and astronomy, Muhammad ibn Musa was a pioneer of astrophysics and celestial mechanics. In the Book on the motion of the orbs, he was the first to discover that the heavenly bodies and celestial spheres were subject to the same laws of physics as Earth, unlike the ancients who believed that the celestial spheres followed their own set of physical laws different from that of Earth.George Saliba (1994). "Early Arabic Critique of Ptolemaic Cosmology: A Ninth-Century Text on the Motion of the Celestial Spheres", Journal for the History of Astronomy 25, p. 115-141 116. ''Astral Motion'' and The Force of Attraction In mechanics and astronomy, Muhammad ibn Musa, in his Astral Motion and The Force of Attraction, discovered that there was a force of attraction between heavenly bodies,K. A. Waheed (1978). Islam and The Origins of Modern Science, p. 27. Islamic Publication Ltd., Lahore. foreshadowing Newton's law of universal gravitation.Robert Briffault (1938). The Making of Humanity, p. 191. Astrology library, from before 1193 AD.]] * A translation of a Chinese work called A Book of Degrees on the Nature of Zodiacal Signs. * Kitāb al-Daraj (The book of degrees), by Ahmad. Other works * Book on the First Motion of the Celestial Sphere (Kitāb Ḥarakāt al‐falak al‐ūlā), containing a critique of the Ptolemaic system. Muhammad in this book denied the existence of the Ptolemaic 9th sphere which Ptolemy thought was responsible for the motion. * Book on the Mathematical Proof by Geometry That There Is Not a Ninth Sphere Outside the Sphere of the Fixed Stars, by Ahmad. * Book on The Construction of the Astrolabe, quoted by al-Biruni. * Book on the Solar Year, was traditionally attributed to Thābit ibn Qurra, but recent research has shown that it was actually by the Bani Musa. * On the Visibility of the Crescent, by Muhammad. * Book on the Beginning of the World, by Muhammad. * Book on the Motion of Celestial Spheres (Kitāb Ḥarakāt al‐aflāk), by Muhammad. * Book of Astronomy (Kitāb al‐Hayʾa), by Muhammad. * A book of zij, by Ahmad * Another book of zij, listed under the Banu Musa, mentioned by Ibn Yunus. Politics Although they were not made famous by their politics, it should be noted that they did have interests outside of the world science. The Banu Musa, mainly the oldest brother Muhammad. They were employed by the caliphs for many different projects, including the canal mentioned above, and they were also a part of a team of 20 hired to build the town of al-D̲j̲aʿfariyya for a caliph named al-Mutawakkil. Taking on these types of civil projects naturally got them involved in the political scene in Baghdad. However, the height of Muhammad's political activity in the palace came towards the end of his life, during a time when Turkish commanders were starting to take control of the state. After al-Mutawakkil died, Mahammad helped al-Mustaʿīn get the nomination in stead of the caliph's brother. When the caliph's brother besieged the city of Baghdad, Mahammad was sent to estimate the size of the army, and when the siege was over he was sent to get the terms of how al-Mustaʿīn would renounce the throne.7 This evidence shows where Mahammad ranks at that time. He was trusted and respected by the highest levels of authority at that time. Other works The Banu Musa wrote almost 20 books the majority of which are now lost. See also *Inventions in the Muslim world *Islamic Golden Age *Islamic science *Islamic astronomy *Islamic mathematics Notes References * * Reviews: Seyyed Hossein Nasr (1998) in ''Isis '''89 (1) pp. 112-113; Charles Burnett (1998) in Bulletin of the School of Oriental and African Studies, University of London 61 (2) p. 406. * *Golden Age of Persia, Richard Nelson Frye, pp. 162–163. *D El-Dabbah, The geometrical treatise of the ninth-century Baghdad mathematicians Banu Musa (Russian), in History Methodology Natur. Sci., No. V, Math. Izdat. (Moscow, 1966), pp. 131–139. * Further reading * (PDF version) * * * * * }} Reviews: Seyyed Hossein Nasr (1998) in ''Isis '''89 (1) pp. 112–113; Charles Burnett (1998) in Bulletin of the School of Oriental and African Studies, University of London 61 (2) p. 406. * D El-Dabbah, The geometrical treatise of the ninth-century Baghdad mathematicians Banu Musa (Russian), in History Methodology Natur. Sci., No. V, Math. Izdat. (Moscow, 1966), pp. 131–139. * Ramon Guardans, A Brief Note on the anwā' Texts of the Late Tenth Century, in: Variantology 4. On Deep Time Relations of Arts, Sciences and Technologies In the Arabic-Islamic World and Beyond, ed. by Siegfried Zielinski and Eckhard Fürlus in cooperation with Daniel Irrgang and Franziska Latell (Cologne: Verlag der Buchhandlung Walther König, 2010), pp. 177–193. http://www.buchhandlung-walther-koenig.de/cat/kwb_45_variantology_4/pid_170000000000790428.aspx * Claus-Peter Haase, Modest Variations — Theoretical Tradition and Practical Innovation in the Mechanical Arts from Antiquity to the Arab Middle Ages, in: Variantology 4. On Deep Time Relations of Arts, Sciences and Technologies In the Arabic-Islamic World and Beyond, ed. by Siegfried Zielinski and Eckhard Fürlus in cooperation with Daniel Irrgang and Franziska Latell (Cologne: Verlag der Buchhandlung Walther König, 2010), pp. 195–213. http://www.buchhandlung-walther-koenig.de/cat/kwb_45_variantology_4/pid_170000000000790428.aspx External links * Manuscript edition of Kitab al-Daraj (a treatise on astrology). 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